#800-5204 DT-4 rolling stock detector by Circuitron. The DT-4 provides an ideal system for spotting a train or even a single piece of rolling stock in a hidden location. The DT-4 contains four completely independent detection circuits combined on one circuit board. Each of the separate sections may be used alone or in conjunction with each other at various points on a layout. It provides a signal at one of the 4 output terminals whenever the corresponding Opto-Sensor is shaded from the ambient room light by a piece of rolling stock. Independent sensitivity controls are provided to adjust each of the 4 circuits to varying lighting conditions.

The DT-4 can be used for any scale and will detect all powered and unpowered rolling stock with no modifications necessary. Each output on the DT-4 provides a connection to 'negative' (ground) when the Opto-Sensor is covered and the output is ON. Like all Circuitron detection circuits, these outputs will each control up to 250 ma. of DC accessories or lamps. The DT-4 is constructed on a 3” x 3” printed circuit board and requires a 6-20 volt DC power source. For greatest stability and ease of adjustment, the power supply should be filtered or regulated.

One of the most useful applications for the Circuitron DT-4 is to light panel lamps for spotting rolling stock in a hidden location. If the Opto-Sensors are installed at set intervals along the track, a train’s progress can be monitored on the control panel, even when it is completely hidden from view. In similar fashion, one of the DT-4’s Opto-Sensors can be located near the end of a blind siding. The output can be used to light a panel light, sound a warning buzzer, or activate a relay which will cut power to the track. Many modelers have found the DT-4 indispensible when used in hidden staging yards. An Opto-Sensor placed at the end of each track, and another just beyond each fouling point gives clear visual indications of where trains are located and whether any are fouling the turnouts.

And the DT-4 is the ideal circuit to activate a multitude of Circuitron train control circuits such as the Time Delay circuit, Turnout Controls, External Relays and the delay section of the AR-2 Automatic Reverse Circuit.

Includes 4 Opto-Sensors (additional Opto-Sensors sold separately). Useable with all scales.